Occupational Health

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Occupational Health Safety

• LSEEE101A
• 9119A

Physical Electrical
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Physical Hazards
These are

• Noise
• Radiation
• Light
• Vibration

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Occupational Health Safety

• LSEEE101A
• 9119A

Noise
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Noise

• What is it?

A travelling wave of pressure These vibrations
can travel through

• Solids
• Liquids
• Gases

Known as a medium
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Noise

• How does it travel through?

• Solids
• Liquids
• Gases

Both longitudinal and transverse waves
Longitudinal waves
Sound cannot travel through vacuum
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Noise

• What is it characteristics?

• Amplitude
• Frequency
• Speed

Volume
Pitch
How fast it travels
For humans ? 12 Hz and 20 kHz
Upper limit generally decreases with age
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Speed
The speed of sound depends on the medium through
which the waves are passing
20 C air at the sea level

• Air
• Fresh Water
• Steel

343 ms-1,1 230 km/h, 767 mph
20 C
1,482 ms-1, 5 335 km/h, 3315 mph
5,960 ms-1, 21 460 km/h, 13 330 mph
The speed is dependant on the mediums

• Density
• Temperature

? Speed
? Density
? Temperature
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Noise

• How do we Measure it?

Sound Pressure in Pascals
p
Sound Pressure Level in decibels
dB
Lp or SPL
dB 2 x 10-5 Pa
But what about frequency
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How Do We Hear
Outer Ear
Pinna or Auricle Gathers sound from the
surrounding environment and sends it down the ear
canal.
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How Do We Hear
Middle Ear

• Tympanic membrane (eardrum)
• 3 small bones
• Malleus
• Incus
• Stapes

carry sound to the inner ear
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How Do We Hear
Inner Ear
Made-up of two main parts

• Vestibular system
• Cochlea

Responsible for balance
Made up of a system of complex hair cells
(sensory cells) send impulses to the auditory
nerve
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Frequency

• The human ear does not hear frequencies equally

The higher the frequency the less sensitive the
ear is
Measurement equipment has to be filtered to
adjust noise levels to match the human ear
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Frequency
D Curve
C Curve
B Curve
A Curve
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Noise

• Excessive noise has various effects on people.
  Examples are

• Tension Headache
• Sleeplessness
• Irritability
• Nervousness
• Increase In Blood Pressure
• Increase In Stomach Acid Level
• Inability To Concentrate

• These are generally considered short term.
• Not considered permanent.

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Noise

• Excessive noise has various long term effects on
  people.

• What are they?
• What noise level is considered dangerous?
• How long must you be exposed before long term
  damage is done?
• What is the maximum peak noise level that any
  worker be exposed to?

Assignment Question
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Noise

• How do we measure it?

If workers are stationary and noise is constant
Basic sound level meter
What type of filtering must it have?

• Placed at the operators ear level
• Also record the length of time the person is
  exposed to that noise

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Noise

• How do we measure it?

If workers are stationary and noise peaks
Basic sound level meter
What type of filtering must it have?
What is the maximum level?
Very loud noise

• Gun fire
• Jet engines
• Nail guns

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Noise

• How do we measure it?

If workers move around or the noise level varies
Personal Noise Exposure Meter
Records and calculates noise exposure with regard
to

• Frequency
• Level
• Length of time

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Noise
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Occupational Health Safety

• LSEEE101A
• 9119A

Radiation
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Radiation
Two basic types

• Ionizing radiation
• Non-ionizing radiation

Visible light is a form of radiation
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Radiation

• Ionizing radiation

Alpha Radiation Beta Radiation Gamma and X
Radiation
A heavy, ejected helium nucleus
Particle Radiation
A light, ejected electron
Electromagnetic Radiation
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• Ionizing radiation

Ionizing radiation
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Radiation

• Ionizing radiation

Alpha Radiation Beta Radiation Gamma and X
Radiation

• Not able to penetrate human skin
• Harmful if the materials are inhaled, swallowed,
  or absorbed through open wounds

Penetrate human skin to the "germinal layer,"
Penetrate several inches into human skin
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Ionizing Radiation

• Disruptive to biological systems, and can cause
• Mutations
• Cancer
• Cataracts
• Radiation sickness
• Radiation burns

Chronic Effects
Acute Effects
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Ionizing Radiation

• Parts of the body that are affected

Most Sensitive Least sensitive
Blood-forming organs Reproductive
organs Skin Bone and teeth Muscle Nervous system
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• Ionizing radiation

Ionizing radiation
Non-ionizing radiation
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Non- Ionizing Radiation

• Low energy form of radiation

Broken down into sections

• Radio waves
• Micro waves
• Infrared light
• Visible light
• Ultraviolet light

Cell damage due to heating effect
Visible-light lasers damage the retina of the eyes

• Burns to skin
• Cataracts to the eyes
• Skin cancer

29
Occupational Health Safety

• LSEEE101A
• 9119A

Lighting
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Lighting

• Clause 46 of the OHS Regulation 2001 states that
  employers must
• Provide adequate lighting to allow workers to
  work safely, move safely, and enter and exit the
  workplace safely (including from emergency exits)
• Ensure that there is not excessive glare or
  reflection
• Ensure that lighting allows persons who are not
  workers to move safely within the place of work.

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Lighting
Provide adequate lighting to allow workers to
work safely, move safely
AS/NZS 1680 series of standards provides lighting
levels for specific industries
Enter and exit the workplace safely (including
from emergency exits)
AS 2293 series of standards provides lighting
levels for Emergency lighting
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Occupational Health Safety

• LSEEE101A
• 9119A

Vibration
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Vibration

• Vibrations are mechanical oscillations, produced
  by regular or irregular period movements of a
  member or body about its rest position

Vibration can be a source problems at an
engineering level, causing

• Damage to equipment
• Loss of control of equipment
• Reduced efficiency of machines

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Vibration

• The effect of vibration on people. Factors
  include
• Point of application of the vibration
• Frequency of the vibration
• Acceleration of the vibration
• Duration of the vibration

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Vibration

• The body of a sitting person responds to vertical
  vibration as follows

• 3- 4 Hz ....Strong resonance in the cervical
  vertebrae
• 4Hz.........Peak of resonance in the lumber
  vertebrae
• 5 Hz........High resonance in the shoulder girdle
  
• 20-30 Hz....High resonance between the head and
  shoulders
• 60-90 Hz....Resonance in the eyeballs
• 100-200 Hz..Resonance in the lower jaw

Musculoskeletal system (muscles, tendons and
bones) can "be a path" for vibration and actually
amplify the vibration as it moves through the body
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Vibration

• Is measured in three distinct patterns or ranges

• Low Frequency
• Middle Frequency
• High Frequency

Cumulative Damage
zero to 2 Hz 2 to 15-20 Hz greater than 20 Hz
Acute Damage
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Vibration
Can affect

• Vision
• Muscles
• Concentration
• Cardiac rhythm

Can cause

• Nausea
• Hyperventilation
• Raised blood pressure
• Increased energy dissipation leading to exhaustion

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Vibration
Can cause long term disorders such as

• Raynaud's Syndrome
• Hand-Arm Vibration Syndrome
• Carpal Tunnel Syndrome
• Tendonitis
• Various bone and joint disorders

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Reduction or Control
Vibration

• Source
• Path
• Receiver

• Reduce vibration intensity/ avoid resonances
• Regulate tool speed/ tool balancing
• Careful tool selection

• Limit exposure time
• Rotate personnel
• Provide rest periods/ minimize weight and
• Use balancers
• Reduce vibration transmission

• Use vibration isolators/ adapt posture
• Reduce grip and push forces/ reduce contact area

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Reduction or Control
Vibration

• Anti-vibration gloves has been the most prevalent
  preventive measure taken by some industries

Are only effective in the high frequency ranges
Most anti-vibration gloves actually amplify
vibrations below 75 Hz while dampening the higher
frequencies
Most handle wraps or foam have this same effect
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Occupational Health Safety

• LSEEE101A
• 9119A

Electricity
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In NSW there are 12 fatalities per year due to
electrocution

• What effect has electricity has on the human body
• The factors that affect the severity of electric
  shock
• Equipment designed to reduce the possibility of
  electric shock
• Work methods around electrical equipment.
• First aid after electric shock

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How does the human body move?
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Electricity sees you as a piece of meat
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What affects the severity of electric shock?

• Time
• Current
• Path

The longer, the more damage
The greater the current, the greater the heat
Does the current go through major organs?

• Heart
• Lungs

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Time Current Graph For Humans
Measured in

• Time in milliseconds
• Current passing through the body in mA

See AS/NZS 60479.1
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Zone 1 Usually No Reaction
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Zone 2 Usually no harmful Physiological effects
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Zone 3 Usually no organic damage Muscular
Contractions Difficulty breathing Possibility of
Cardiac Arrest
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Zone 4 Includes Zone 3
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Zone 4 C1 Probability of Ventricular Fibrillation
increased to 5
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Zone 4 C2 Probability of Ventricular Fibrillation
increased to 50
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Zone 4 C3 Probability of Ventricular Fibrillation
increased to above 50
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Protection Systems
Fuses Circuit Breakers DO NOT directly protect
against electrocution
What is the current required to cause burns in
the human body?
What is the trip current of a Circuit breaker
supplying power points?
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Protection Systems

• AS/NZS 30002007

1.5.3 Protection against electric shock 1.5.3.1
Scope Protection shall be provided against shock
current arising from contact with parts that are
live in normal service (direct contact) or parts
that become live under fault conditions (indirect
contact).
Fuses Circuit breakers only protect against
indirect contact
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Protection Systems

• Protection Against Direct Contact

Safety Switch Residual Current Device (RCD)
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RCDs
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No Fault
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(No Transcript)
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Fault
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Working On Electrical Equipment

• Must avoid working on live equipment
• See Workcovers Code of practice Low Voltage
  Electrical Work  Publication No 0964
• To make dead circuit must be isolated

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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority
3. Method of isolation
4. Test for supply
5. Isolate
6. Danger Tag
7. Test
8. Test tester

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Isolation Procedure Order

1. Assess the need

Do you have the skills, qualifications, knowledge
of the equipment to safely isolate a piece of
equipment?
Equipment is normally remote from the isolation
point. Two people are generally required
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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority

An isolation point may affect other machinery
May create a dangerous situation on other
processes that are interlinked
Many companies require a Clearance to Isolate
authorisation before isolation commences.
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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority
3. Method of isolation

Can be many locations in the electrical
installation
Main Switch Circuit Protection Isolation switch
near device
Isolation point must be able to LOCKED OUT
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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority
3. Method of isolation
4. Test for supply

Test equipment must comply with Australian
Standards
Tests that there is a supply to the device
Be aware of automatic controlled equipment
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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority
3. Method of isolation
4. Test for supply
5. Isolate

Isolation point must be able to LOCKED OUT
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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority
3. Method of isolation
4. Test for supply
5. Isolate
6. Danger Tag

Two types of tag Danger Out of Service
Must be installed in such a way that it has to be
removed to operate isolation point
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Out of Service
Used to Protect Equipment Only
Can be removed by anybody with authorisation
Can stay on equipment until repaired or replaced
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Personal Danger
Used to Protect Life
Can only be removed by the person who placed it
there
Has to be removed when worker leaves danger area
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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority
3. Method of isolation
4. Test for supply
5. Isolate
6. Danger Tag
7. Test

Confirms that the correct isolation point has
been used
Test equipment must comply with Australian
Standards
Measure between Active Neutral Active Earth
Exposed Conductive parts or Ground Active
Other Actives
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Isolation Procedure Order

1. Assess the need
2. Notify affected people/Seek authority
3. Method of isolation
4. Test for supply
5. Isolate
6. Danger Tag
7. Test
8. Test tester

Confirms that tester is functioning correctly
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Caution
Why is the attempt to operate isolation
procedure not an effective method of verifying
that a circuit is de-energized?
mechanical failure of a switch contact cannot be
determined by the attempt-to-operate method
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THE END?